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LAUNCH ISSUE!
April 2013
Battery technologies
Hybrid systems
Fuel cells
Electric motors
Emissions reduction technologies
PLANET SOLAR
The development story behind
the first vessel to travel around
the world with zero fuel and
zero CO2 emissions
UKIP Media & Events Ltd
April 2013
US NAVY GOES ELECTRIC
The US Navy is adopting hybrid electric
drive systems for its fleet of destroyers
– is this just the start of things to come?
OEM INTERVIEW
Oskar Levander, Rolls-Royce Marine’s
engineering VP, discusses tomorrow’s
green propulsion technologies
HYDROGEN AGENDA
How next-generation fuel cell
designs will shape the marine
world over the next five years
US NAVY GOES ELECTRIC
US NAVY GOES ELECTRIC
Reporting
for duty
The US Navy has confirmed plans to introduce
advanced hybrid electric drive systems to its
fleet of destroyers. The technology promises
to increase fuel efficiency, reducing the amount
of money it spends on oil – but just what are
the wider ramifications of this development?
WORDS: HARRY REYNOLDS
The USS Truxtun (DDG 103)
is a US Navy Arleigh
Burke-class hybrid-powered
destroyer featuring battery
and mechanical drive
advanced technology
I
n what is being seen as a landmark development for
the marine and defense sectors, as well as the wider
sustainable transportation arena, the US Navy (USN)
has confirmed it is introducing hybrid electric drive
(HED) systems to its Arleigh Burke (DDG 51)
destroyers, with the aim being to increase the
overall fuel efficiency of the fleet.
Discussing the move, Dr Timothy McCoy, director of
the electric ships office (PMS 320) at Naval Sea Systems
Command (NAVSEA), says, “It is a big ship class that
forms about 40% of our fleet fuel usage. Therefore
if we can save a little bit of fuel on that ship, that
translates into a lot of savings for the Navy as a whole.”
McCoy says that following an industry-wide bidding
process for the project, NAVSEA awarded a US$119m
20 // April 2013 // Electric & Hybrid Marine Technology International
contract to L-3 Marine & Power Systems for the
development phase for a HED prototype system.
The plan is for the base contract to last one year
and will consist of a design review before material
is released, followed by a further detailed review
after which the green light will be given for the
manufacture of pre-production units.
One pre-production unit will go for environmental,
shock and vibration testing, and another will go to
the USN’s land-based testing site in Philadelphia for
integration with the ship testing machinery control
and electric systems. After that, production units
will be installed on the ships. The plan is to retrofit
all 36 Flight IIA ships of the Arleigh Burke-class, with
the first ship to be completed in 2016. “All the other
Electric & Hybrid Marine Technology International // April 2013 // 21
US NAVY GOES ELECTRIC
US NAVY GOES ELECTRIC
ships are options in the contract, so are subject to in-year
funding like everything is. We are planning at least two
installs in the first year,” McCoy says.
“There is set budget for it and now that we have a
contract we know what the hardware is going to be, but
we are still working out what the shipyard’s install cost
will be. So based on what the total cost is going to be,
that will dictate how many units we can do each year.”
“What we are able to do is run fewer
engines but run them more heavily
loaded. In the case of the DDG 51s,
with three gas turbine generators on
board, we are able to turn off all of the
main propulsion engines and use the
margin on the generator sets to propel
the ship up to a moderate speed”
Oil savings
The installation of HED propulsion systems across the
fleet is expected to save at least 5,000 barrels of oil per
ship per year, and could reach up to 10,000 barrels per
ship depending on the speed profile and operational tempo.
However, the USN’s experience with HED systems has
been limited until recently. Initial paper studies started in
2007, and later that year the PMS 320 was created in order
to investigate alternative forms of ship propulsion for the
organization. The entire project received a timely boost in
mid-2008 when the price of crude oil hit a new high, and
while costs have since fallen on a global basis, the price of
crude oil has been steadily rising again, underscoring the
importance of HED technology for the USN.
The USN recently redesigned its amphibious assault
ships (LHDs) to eliminate the use of a steam propulsion
plant. The meant that when the organization
was fitting its latest ship, the USS Makin
Island, it opted for an eco-friendly gas
turbine unit and an all-electric auxiliary
system from General Electric that uses
induction motor and low-voltage modulator
drive technology. The ship was
commissioned in 2009 as the USN’s first
HED warship, and following its maiden
voyage lasting about two months, the
commander reported that the ship had saved
about US$2m in fuel.
The result of the project is that HED systems will be
installed on the Navy’s new America-class amphibious
assault ships (LHA 6), two of which are under construction.
The Navy could look to this program as a roadmap
for the future use of HED, but the US organization could
Dr Timothy McCoy, director, electric ships office, Naval Sea Systems Command
Many navies around the world are
increasingly looking to hybrid electric
drive technology in an effort to reduce
total fuel expenditure. The UK is seen
as a leader in this field, having used
HED propulsion systems for decades
also cast an eye to examples overseas and specifically
to the UK, where the Royal Navy’s Type 23 frigates have
been using HED propulsion systems for decades. But
these new US ships – and the Makin Island – have been
built with HED specifically in mind, while the system for
the DDG 51s will be retrofitted to the existing machinery.
Work on the DDG 51s started in July 2009, when
NAVSEA awarded General Atomics and DRS Technologies
a US$32m contract to develop a proof-of-concept
system integrating an electric drive with the main
reduction gear using an existing quill shaft for land
testing at the Philadelphia site.
This was followed in August 2010 with a US$6.56m
contract for a technical demonstrator using a DRS 1.5MW
permanent magnetic motor. NAVSEA used the results
of the testing undertaken at the land site to then issue
a request for proposals from the industry in October 2011
to competitively procure a production system. L-3 was
selected to take the project forward.
Better efficiency at low speeds
The USN first started
looking into HED systems
during an initial paper
study in 2007. Today, the
organization has begun
applying the technology
to real-world applications
22 // April 2013 // Electric & Hybrid Marine Technology International
In the ship propulsion world, a hybrid electric drive
system means a combined battery and mechanical
drive combination that uses the electric power generator
turbines, which are run on petroleum and power the
ship’s combat and crew habitability systems, as well as
driving the ship’s propulsion at low speeds. Fuel is still
being used, but at a far lower rate, and crucially for the
operator, power is not being wasted.
The Flight IIA Arleigh Burke destroyers are fitted
with four GE LM2500 gas turbine engines, which are
the prime movers, providing a total 74.6MW of power
to propel the ships at the top speeds required when
on operations. However, according to McCoy, these
engines are “notoriously inefficient at part load – they
like to run full power”.
USN ships have to be designed for maximum strain
conditions: they would not be effective warships
otherwise, so they are able to withstand adverse
environments from the hottest to the coldest of days,
and these calculations include the need to move at high
speeds. But all this means that the powerful LM2500
engines, which are best operating in extreme operational
conditions, perform less efficiently at lower speeds.
The Flight IIAs are fitted with three Rolls-Royce
AG9140 generator sets powered by gas turbines that
provide electricity for the combat systems and the crew
habitability systems. Two are normally operational at one
time, providing 6MW of power, with the third acting as
an auxiliary. However, less than
half of the power produced by the
two generators is used and
therefore the HED system will
use this extra capacity to drive
the propulsion system, which
means the ship can move at lower
speeds without turning on the
LM2500 engines.
The DDG 51s typically spend
half of the time moving at low
speeds under 15kts, so the Navy
anticipates that using an HED
system for power propulsion
would increase the efficiency
of the ships by 9-15%. Putting
an electric motor and generator
on each of the main reduction
gear will allow the main
propulsion LM2500 engines to
be shut down when the ship
moves at lower speed levels.
The plan for the DDG 51 Flight
IIAs is for the port shaft to be
fitted with the system, with the
Left and above: The
pioneering Makin Island
has been built specifically
for HED technology, unlike
the retrofitted DDG 51s.
Makin benefits from a
gas turbine unit and an
all-electric auxiliary
system from General
Electric that uses induction
motor and a low-voltage
modulator drive system
Electric & Hybrid Marine Technology International // April 2013 // 23
US NAVY GOES ELECTRIC
UK Royal Navy MARS
tankers benefit from
advanced new GE hybrid
propulsion configuration
that is more fuel-efficient
than standard propulsion
systems on the market
UK Navy sources
GE expertise
General Electric is also supplying its acclaimed
electrical propulsion drivetrain technology
for the UK’s Royal Fleet Auxiliary’s (RFA)
new Military Afloat Reach and Sustainability
(MARS) tankers.
When completed, the four 37,000-ton
MARS tankers will be the UK’s next-generation
class of large fast-fleet tankers and will
deliver fuel and fresh water to Royal Navy
vessels around the world. GE’s drivetrain will
be installed as a key part of the ships’ hybrid
propulsion configuration, which is inherently
more fuel-efficient than conventional
propulsion systems. The next-generation
MARS tankers are due to enter service in
early 2016.
The RFA is replacing its existing, singlehulled tankers to meet IMO pollution
regulations, as well as the more stringent
European Commission environmental
regulations. The latest amendment to the
MARPOL regulations requires tankers to be
double-hulled.
GE’s hybrid propulsion system combines
electrical and mechanical propulsion
technology to turn the ship’s propeller
throughout its operating range of speeds.
When the ship operates at moderate and low
speeds, the propeller shaft is turned using
GE’s electric motor and variable-speed drive
controller system. Meanwhile, at high speeds
the diesel engine or gas turbine is connected
directly to the propeller through a gearbox.
“Our electrical drivetrain technology will
offer the RFA’s new fleet of MARS tankers a
highly energy efficient, flexible and integrated
power and propulsion system to direct
power as needed in support of their military
operations,” says Paul English, marine leader
at GE’s power conversion business.
GE is also supplying its electric drives
Daewoo Shipbuilding & Marine Engineering,
which was awarded the contract for the four
MARS tankers by the UK MoD last year.
starboard shaft unaltered and used in a
trailing mode. The industry is keen to present
a two-shaft solution with changes to both
port and starboard, but changing a single
shaft was deemed to be the cheaper
engineering option.
“What we are able to do is run fewer
engines but run them more heavily loaded,”
continues McCoy. “In the case of the
DDG 51s, with three gas turbine generators
on board, we are able to turn off all of the
main propulsion engines and use the margin
on the generator sets to propel the ship up
to a moderate speed.
“The same with the Makin Island – she has
diesel generator sets but she has gas turbine
voltage, variable frequency AC, because
in order to change the speed of an AC
motor, whether it be a permanent magnet
motor, synchronous motor or an induction
motor, you have to change the frequency,”
explains McCoy.
“Every other piece of equipment on the ship
wants a constant frequency, so what these
variable speed drives do is take in the
constant frequency and turn it into a variable
frequency, variable voltage. So when the
captain wants to change speed he is able to
do that. This is just an electronic way of
making that happen.”
Using records from the NAVSEA’s
Incentivized Energy Conservation team,
“It is a big ship class that forms about 40%
of our fleet fuel usage. Therefore if we can
save a little bit of fuel on that ship, that
translates into a lot of savings for the Navy”
Dr Timothy McCoy, director, electric ships office, Naval Sea Systems Command
propulsion engines, so up to about 12kts
we can turn off all the gas turbine engines
and just run the diesel generators. That
way she burns less fuel: you are running
fewer engines, but the ones you are
running are more heavily loaded.
“For the gas turbines, that translates
directly into greater fuel economy for
the diesel engine.”
The other main piece of equipment that is
involved in this process is the variable speed
drive, which is a set of advanced electronic
equipment that is predominantly installed
in a large grey cabinet.
The equipment takes in the electricity
coming off the ships bus (usually 60Hz,
three-phase AC electricity) and converts it
to DC. “It then chops it up into a variable
24 // April 2013 // Electric & Hybrid Marine Technology International
it can be revealed that in FY2005, the
23 DDG 51 ships in service used an average
of 157,466.34 barrels of fuel each per year,
making a total of 3.6 million barrels used
by the Arleigh Burkes alone.
Since then, there have been efforts to
conserve the amount of fuel used, but the
number of ships in that class has doubled.
In FY2013 there were 50 DDG 51 ships in
service, each using an average 155,430.76
barrels, making a total of 7.7 million barrels
of fuel consumed by the destroyers.
Therefore considering the scale of fuel
usage by just one section of the surface fleet,
any fuel efficiencies that can be introduced
through applying new systems will be
welcome news for those trying to balance
the budget and realize cost savings.